Improving thermal conductivity and shear strength of carbon nanotubes/epoxy composites via thiol-ene click reaction

This study investigates the effect of the thiol-ene click reaction on thermal conductivity and shear strength of the epoxy composites reinforced by various silane-functionalized hybrids of sulfhydryl-grafted multi-walled carbon nanotubes (SH-MWCNTs) and vinyl-grafted MWCNTs (CC-MWCNTs). The results of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM) show that the sulfhydryl groups and vinyl groups are successfully grafted onto the surface of MWCNTs, after treatment of MWCNT with triethoxyvinylsilane and 3-mercaptopropyltrimethoxysilane, respectively. Scanning electron microscopy (SEM), HotDisk thermal constant analyzer (HotDisk), optical microscope, and differential scanning calorimetry (DSC) are used to characterize the resultant composites. It is demonstrated that the hybrid of 75 wt % SH-MWCNTs and 25 wt % CC-MWCNTs has better dispersion and stability in epoxy matrix, and shows a stronger synergistic effect in improving the thermal conductivity of epoxy composite via the thiol-ene click reaction with 2,2-azobis(2-methylpropionitrile) as thermal initiator. Furthermore, the tensile shear strength results of MWCNT/epoxy composites and the optical microscopy photographs of shear failure section indicate that the composite with the hybrid MWCNTs has higher shear strength than that with raw MWCNTs. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44579.